This invention relates to a portable, high power arc lamp system. More particularly, this invention relates to a battery powered, high power, arc lamp system suited for low duty cycle applications such as photocurable composite and resin curing and tooth whitening. The lamp may be a short arc xenon, argon, or utilize another gas. The invention further relates to using a system of the present invention to cure photocurable materials and in tooth whitening procedures.
Arc lamps, particularly short arc xenon lamps, are known in the art for various applications, such as infrared and visual searchlights, fiber optic illumination, spectroscopy, stadium lighting, stage and screen lighting, automobile headlights, and microscopy. The spectral distribution of xenon lamps is similar to that of natural daylight.
Arc lamps have also been utilized for composite and resin curing applications. For example, U.S. Pat. No. 5,290,169 to Friedman et al. discloses a hand held light curing gun for curing dental composites. The lamp may be tungsten/halogen, mercury vapor, short arc xenon, or metal-halide. An optical light guide is used to transmit the light output by the lamp to the dental restoration. U.S. Pat. No. 4,948,215 to Friedman also discloses a hand held dental curing light used in combination with an optic light guide selected from a plurality of autofocus optic light guides for transmitting maximum power density to different sized dental materials.
Existing dental curing lamps are used in conjunction with photocurable dental materials that replace gold, porcelain, and silver amalgam. However, the power output of such systems is relatively low, so that curing can take a substantial amount of time. The lower the power output, the longer it takes to cure the composite. In addition, the photocurable materials used in dental applications generally exhibit improved properties when they are cured at a faster rate. Furthermore, as discussed herein, it has been found that resins and composites cured at higher power levels require less total energy than those cured at lower power levels. Thus, there is a need for a high power dental curing lamp that is compatible with existing dental office operatories.
In addition, the use of light, and in particular light in the blue/green spectrum, is beneficial in tooth whitening procedures because light in this wavelength tends to be more readily absorbed by yellow/brown colored stain molecules but mostly reflected by the red colored tooth pulp in vital teeth. One such tooth whitening procedure utilizes a whitening agent, such as a peroxide compound, in combination with laser light from an argon laser to generate free oxygen radicals to accelerate the whitening process. Such procedures, however, can require a lengthy office visit due to the amount of time each tooth must be exposed to laser light in order to effectuate the whitening process. This is because the argon lasers used in these procedures typically have output powers in the range of 250 mW-500 mW.
U.S. Pat. No. 4,661,070 to Friedman discloses a method for bleaching discolored teeth using a concentrated solution of hydrogen peroxide and a source of light comprising ultraviolet energy in the 320 to 420 nanometer range and infrared energy in the 700 to 1200 nanometer range. The lamp may be tungsten halogen, mercury vapor, short-arc xenon, or metal halide. An elliptical reflector directs the light into a light guide. Friedman, however, does not disclose the use of a high power lamp and in fact does not mention power levels or exposure times. Moreover, Friedman filters out light in the 420 to 700 nanometer range, i.e., visible light, which applicants have found to be most beneficial for both curing and tooth-whitening applications, as discussed above.
In order to reduce the time required to effect composite curing as well as tooth whitening, a higher power light source is needed. In particular, a light source with a power input of 1500-3000 W is desirable.
Several problems exist, however, in designing such a system utilizing 110 V alternating current, the standard house current in the United States that is typically available in dental offices. First, many building codes impose limits on the permissible current draw of electrical appliances, which therefore limits the maximum power output of an arc lamp system. Thus, to obtain high power outputs, it is typically necessary to use 220 V to reduce current draws. However, 220 V power is typically not readily available in dental office operatories and other office settings. In addition, to the extent higher power outputs can be achieved using standard house current, costly linear or inverter power supplies are required in order to provide a low voltage, high current output suitable to drive an arc lamp. This is because arc lamps require specially designed power supplies tailored to the starting and operational requirements of the lamp, with limits on in-rush current and peak-to-peak current ripple. Moreover, even if 220 V power is available, there remains the problem of power spikes and ripple that result from the use of ac power and can shorten the life of arc lamps.
In dental curing and tooth whitening applications, the energy requirements are determined in accordance with a total amount of energy to be imparted to a given tooth. Typically, 20 joules of total energy per tooth is the maximum energy provided for both curing and tooth whitening applications. This figure is used to ensure that the pulp in vital teeth is not damaged. Existing curing lamps and lasers used for curing and whitening procedures generally operate at power levels of less than 1 watt. Thus, it takes in the range of 20-60 seconds to impart the required amount of energy to a tooth.
Both curing and whitening procedures can be improved through the use of higher power light sources that reduce the exposure time required per tooth application. This is because photocurable composites and resins typically exhibit improved properties the faster they are cured. Similarly, with regard to whitening procedures using peroxide compounds, the bleaching efficiency of the peroxide is improved because as more energy is applied, more of the peroxide is broken down into free oxygen radicals. The longer the peroxide is resident on a tooth, the greater the amount of molecular oxygen produced, which does not have nearly the same bleaching effect as free oxygen radicals.
Therefore, there is a need for a high power arc lamp system for curing composites and resins as well as tooth whitening applications.
In addition, there is a need for an improved procedure for both composite and resin curing where the composites and resins are cured at a higher power level to both reduce the cure time and improve the properties of the cured material.
There is additionally a need for an improved tooth whitening procedure using a high power light source to both reduce the duration of the whitening procedure and improve the effectiveness of the bleaching compositions.